@startuml

abstract Activity

Activity <|-- Communication
Communication : Each comm involves 2 actors (sender/receiver)

Communication -- Mailbox : < factory of

Activity <|-- Execution

Execution -- Host : < factory of

Activity <|-- Io
Io : To be refined into read / write?

Io -- Disk : < factory of

Activity <|-- Sleep
Sleep : Blocks an actor without consuming resources
Sleep : May still be located on resource (to detect failures)
Sleep -- Actor : < factory of

Activity <|-- RawActivity
RawActivity : Does not use the platform

RawActivity -- Mutex : < factory of
RawActivity -- Semaphore : < factory of

@enduml